class Car():
    def __init__(self, maker):
        self.maker = maker

    def fullTank(self):
        print("tank fulling...")

    def showInfo(self):
      print ('这辆车是：' + self.maker + '牌的。')


class Battery():
    def __init__(self, buttery_size="70"):
        self.buttery_size = buttery_size

    def showBattery(self):
        print('当前剩余电量为：' + self.buttery_size + '%.')

class ElectricCar(Car):
    def __init__(self, maker):
        super().__init__(maker)
        self.battery = Battery()

myTesla = ElectricCar('tesla')
myTesla.showInfo()
# 这辆车是：tesla牌的。
myTesla.battery.showBattery()
# 当前剩余电量为：70%.
